Impedance phase faults location algorithm for UHV transmission lines

The precision of impedance fault location algorithm is deteriorated by the extremely large shunt capacitance in UHV line. And the traditional improved ways are all invalid caused by the nonlinearity of measurement impedance in relay and the frequent variations of operation modes in UHV system. In response to this question, a novel impedance fault location algorithm is proposed for phase faults. It is based on the precondition that the phases of negative sequence current at meter location can precisely describe the phase information of fault voltage. And then calculate the measurement impedance at time of zero-crossing point of fault voltage to avoid the bad influence of fault resistance. The algorithm is immune to the influence of shunt capacitance with distributed parameters modeling. Theory analyses and simulation cases proved its good location accuracy.